Page 1 of 1

What is layer '0' used for?

Posted: Wed Jul 23, 2014 11:41 am
by cjs94
Hi,

In a mechanical drawing what is intended to be drawn on layer '0', as opposed to, say, the Outline layer? (I'm referring to the AEC layer template shipped with QCAD.)

Chris

Re: What is layer '0' used for?

Posted: Wed Jul 23, 2014 11:50 am
by andrew
Layer '0' is for historical reasons always present and cannot be deleted.

In most cases, it should not be used unless you are working on a very simple drawing that does not use layers. In this simple case, you might want to create everything on layer '0' and not worry about layers at all.

Re: What is layer '0' used for?

Posted: Wed Jul 23, 2014 12:25 pm
by Clive
Traditionally Blocks (symbols) can be created on Layer 0 in programs like AutoCAD and Microstation with Colour, Line type and Line width set to 'by layer', once inserted the block/symbol will then have the attributes of the layer upon which it is inserted. Hope this makes sense e_confused

Re: What is layer '0' used for?

Posted: Fri Jul 25, 2014 6:09 pm
by riverbuoy
Hi Clive,
Clive wrote:Traditionally Blocks (symbols) can be created on Layer 0 in programs like AutoCAD and Microstation with Colour, Line type and Line width set to 'by layer', once inserted the block/symbol will then have the attributes of the layer upon which it is inserted. Hope this makes sense e_confused
That is how it works in Autocad.
However, in QCAD, if you draw your entities on layer 0, and set Colour, Linetype and Lineweight to 'ByLayer', and then add those entities to a block, when the block is inserted the entities always take on the values of layer 0, not the values of the layer on which it is inserted. You need to set the Colour, Linetype and Lineweight to 'ByBlock' to have the entities take on the values of the layer on which it is inserted.

riverbuoy

Re: What is layer '0' used for?

Posted: Fri Jul 25, 2014 9:20 pm
by Clive
riverbuoy wrote:That is how it works in Autocad ....However, in QCAD
Ah, yes the story continues, thanks for the next chapter.

Re: What is layer '0' used for?

Posted: Fri Jul 25, 2014 10:06 pm
by Husky
Hi everybody 8)
riverbuoy wrote:... to have the entities take on the values of the layer on which it is inserted.
For what do I need that? Usually my blocks are build with using a couple different layers - like this one:
Husky-2014.07.25-05.png
Husky-2014.07.25-05.png (1.38 KiB) Viewed 12179 times
... and I'm pretty happy that this block doesn't adopts the actual Layer attributes. 8)

If I need a block with just one layer I would design this block in first place onto the right layer. Isn't that right?

Re: What is layer '0' used for?

Posted: Fri Jul 25, 2014 10:09 pm
by Clive
Husky wrote:... and I'm pretty happy that this block doesn't adopts the actual Layer attributes. 8)
agreed :wink:

Re: What is layer '0' used for?

Posted: Sun Feb 05, 2017 8:33 pm
by PCe
Using layer 0 to draw library object has the advantage of NOT creating any new layer (with names you can not figure out any more what they should mean) when you insert the block in a design maybe already crowded with very meaningful layer and sublayernames...
Layers other than 0 used to define your block will pop up in your layer list and create some hard to understand behavior like "parts of the object disappear when hiding the unwanted layers". Am I right? Somewhat puzzling to me.
I would prefer that a block/library object would be just ONE object belonging to the layer where it is placed on with no addition of new, unwanted layers to the list.
Am I missing the point?
PCe

Re: What is layer '0' used for?

Posted: Sun Feb 05, 2017 10:00 pm
by Husky
Basically there is no right or wrong doing! It depends on what everybody needs to be accomplished with his block/library management.
PCe wrote:... Layers other than 0 used to define your block will pop up in your layer list and create some hard to understand behavior like "parts of the object disappear when hiding the unwanted layers". Am I right? Somewhat puzzling to me.
Yes and no. To show the correct Linetyp like dashed for invisible or dash/dot for axis/symmetry is a very important information in your drawing. Just to draw everything in the same Linetyp will put a drawing to the status "unusable'.
PCe wrote:I would prefer that a block/library object would be just ONE object belonging to the layer where it is placed on with no addition of new, unwanted layers to the list.
Possible!

Check this test drawing. I have a block which is sometimes needed as it is (1) - sometimes hidden behind other objects (2). I needed an easy way to insert this block for this two occasions without creating or watching additional layer or the visible/invisible status. This will work for the two mentioned situations - it will fail if the block is partly behind an other object. Only then I have to modify the inserted block.
Husky-2017.02.05-01.png
Husky-2017.02.05-01.png (11.43 KiB) Viewed 10049 times
The behavior is based on this settings:
Husky-2017.02.05-02.png
Husky-2017.02.05-02.png (35.94 KiB) Viewed 10049 times
Now you: Can you figure out what I have done to receive this effect?
layer test.dxf
(103.2 KiB) Downloaded 406 times

Re: What is layer '0' used for?

Posted: Sun Feb 05, 2017 10:52 pm
by PCe
Husky,
you overestimate my understanding of the issue... ;-) I don' really see your point. Your block is drawn on layer 0 (everything) with different line types and colors which is preserved (I welcome this behavior) when using the block.
Can you please comment on "Entities in blocks on layer 0 take on attributes of .... (compatibility)"?
What's the effect?
TNX - PCe

Re: What is layer '0' used for?

Posted: Mon Feb 06, 2017 12:04 am
by Husky
PCe wrote:Husky,
you overestimate my understanding of the issue... ;-)
I don't think so - you already figured out what I have done with the block .... :wink:
PCe wrote:Your block is drawn on layer 0 (everything) with different line types and colors which is preserved.
Correct!
PCe wrote:Can you please comment on "Entities in blocks on layer 0 take on attributes of .... (compatibility)"?
What's the effect?
The benefit is that every entities in the block which has been drawn on 0 WITHOUT getting it own attributes like color, linetyp etc. will adopt the attributes from the layer on which it is insert.

Make a test with my example drawing: Insert the block on layer 0 and then insert the same block on layer Hidden. You will see that only the outline will adopt the Attributes of the chosen layer. Create a couple more layers with different attributes to test it with them too.